The invention is based on a wiper arm for a windshield wiper.
Known windshield wipers have a wiper arm that comprises a fastening part and a joint member that has a wiper rod and is pivotably connected to the fastening part. A wiper blade, which as a rule is constructed of a wiper strip holder and a wiper strip, is pivotably connected to the wiper rod.
The joint member, on its end toward the fastening part, has a spring chamber for a tension spring. The spring chamber is open toward the windshield, and toward the wiper rod it has an angle element, such as an eye, from which a retaining bracket of the tension spring is suspended. The other end of the tension spring engages a C-shaped bracket, which is suspended from an angle element of the fastening part. The C-shaped bracket can also be formed onto the tension spring. The joint member is braced via a hub on a joint pin of the fastening part. The joint thus formed, also called a swing-down joint, and the angle element of the tension spring are arranged relative to one another such that the tension spring pulls the joint member and the wiper rod in the direction of a windshield. Thus under the force of the tension spring, the wiper blade rests on the windshield and is limited by it in its operating position.
For cleaning or mounting of the wiper blade, the joint member of the windshield wiper is swung down from the windshield. To that end, the joint member is pivoted about the swing-down joint, and in the range of a swing-down angle of approximately 60 to 80°, the tension of the tension spring must first be overcome. In the swing-down position, the spring no longer pulls the joint member toward the vehicle window; instead, it pulls either a contact face, which is formed onto the joint member, or the C-shaped bracket in the swing-down direction against a limiting stop on the fastening part. To swing the wiper blade back against the windshield, the joint member must be pivoted about the pivot shaft again with a defined force.
To improve the aerodynamic properties of a vehicle, the windshield wipers, in their parking position, are increasingly stored away in a concealed manner in a so-called hood gap between the hood over the engine and the windshield. A wiper system of this kind is known for instance from German Patent Disclosure DE 38 10 017 A1. So that the joint member on being swung down by the usual angle will not strike the hood and damage it, a limiting stop is provided, permitting it to be swung down only within a smaller angular range, in which the tension spring does not yet generate any force in the swing-down direction. In this swing-down position, which does suffice to clean the windshield but makes changing the wiper blade more difficult, the joint member is held by a spring detent that is formed by the tension spring and a cam-shoulder assembly.
Some swing-down joints, for instance in accordance with German Patent Disclosure DE 37 09 994 A1, have a hub that is solidly joined to the fastening part and is open toward the joint member and is engaged by a boltlike pivot shaft that is solidly joined to the joint member. In the built-in state, the joint member with the wiper blade are held in a stable position by the hub and the vehicle window, while in the swing-down position they are held in a stable position by the hub and the limiting stop. Accordingly there is no risk that the joint member will be rotated outward toward the open side of the hub.
In the preassembled state, for instance for shipping, there is the risk that a slight exertion of force on the premounted wiper arm, for instance from jarring during shipping or from careless handling, the pivot shaft will slide out of the hub, and the swing-down joint will fall apart into its individual components. This necessitates additional installation work and has the risk the parts will be lost.